Ventricular fibrillation (VF) is the most common etiology leading to sudden cardiac death. Early defibrillation and non-interrupted Cardio Pulmonary Resuscitation (CPR) are the most important determinants for restoration of spontaneous circulation in patients with VF. The occurrence of VF out of hospital makes early defibrillation hard to be realized. Fortunately, the VF waveform analysis such as amplitude spectrum analysis (AMSA) could help estimate the duration of VF, determine the shockability by assessing the VF waveform as being fine or coarse, and predict the probability of successful defibrillation, and has been applied to the conventional Automatic External Defibrillator (AED) for providing early defibrillation during the occurrence of VF out of hospital.
Although studies have demonstrated interruption of CPR greatly decreases the probability of successful resuscitation, non-interrupted CPR during recording Electrocardiography (ECG) for the VF waveform analysis is still a challenge. As shown in FIG. 1, chest compression related signals appearing in ECG which are caused from the CPR are often nonstationary and nonlinear rendering the linear-based analytic methods such as Fourier or wavelet-based analysis ineffective. Even though AMSA was claimed to be estimated with no interruption of CPR, CPR artifacts such as chest compression related signals are supposed to deteriorate the reliability and accuracy of VF waveform analysis because of power leak in spectrum analysis. As a result, it is usually required to discontinue CPR during recording ECG for the current VF waveform analysis to avoid the chest compression related signals mixing in ECG.
There are many solutions to the above challenge. The conventional filtering methods such as fixed coefficient high-pass filtering and adaptive band-stop filtering are still not desirable. Therefore, persons of ordinary skill in the art are imperative to develop a new analysis method which can be applied on the ECG recorded during uninterrupted CPR to not only reconstruct the morphology of VF waveforms but also to preserve the waveform parameter (i.e. AMSA) of shockability.